doc: document Go 1.9.3

Change-Id: Ic7a5d3118754b34ab0652fcef889259a03baebc3
Reviewed-on: https://go-review.googlesource.com/88536Reviewed-by: Ian Lance Taylor <iant@golang.org>

doc/devel/release.html

@@ -49,6 +49,14 @@ See the <a href="https://github.com/golang/go/issues?q=milestone%3AGo1.9.2">Go
 1.9.2 milestone</a> on our issue tracker for details.
 </p>
 
+<p>
+go1.9.3 (released 2018/01/19) includes fixes to the compiler, runtime,
+and the <code>database/sql</code>, <code>math/big</code>, <code>net/http</code>,
+and <code>net/url</code> packages.
+See the <a href="https://github.com/golang/go/issues?q=milestone%3AGo1.9.3">Go
+1.9.3 milestone</a> on our issue tracker for details.
+</p>
+
 <h2 id="go1.8">go1.8 (released 2017/02/16)</h2>
 
 <p>
@@ -272,7 +280,7 @@ See the <a href="https://github.com/golang/go/commits/go1.3.2">change history</a
 </p>
 
 <p>
-go1.3.3 (released 2014/09/30) includes further bug fixes to cgo, the runtime package, and the nacl port. 
+go1.3.3 (released 2014/09/30) includes further bug fixes to cgo, the runtime package, and the nacl port.
 See the <a href="https://github.com/golang/go/commits/go1.3.3">change history</a> for details.
 </p>
 
@@ -336,7 +344,7 @@ about the future of Go 1.
 </p>
 
 <p>
-The go1 release corresponds to 
+The go1 release corresponds to
 <code><a href="weekly.html#2012-03-27">weekly.2012-03-27</a></code>.
 </p>
 
@@ -352,7 +360,7 @@ It also includes several minor code and documentation fixes.
 
 <p>
 go1.0.2 (released 2012/06/13) was issued to fix two bugs in the implementation
-of maps using struct or array keys: 
+of maps using struct or array keys:
 <a href="//golang.org/issue/3695">issue 3695</a> and
 <a href="//golang.org/issue/3573">issue 3573</a>.
 It also includes many minor code and documentation fixes.